wc -l medals.txt
grep -E "中国|中国香港|中国台北" medals.txt | sort -k2,2nr -k3,3nr -k4,4nr
sort -k4,4nr -t',' medals.txt | head -n 5 | cut -d',' -f1
echo "金牌前五记录："; sort -t',' -k2 -nr medals.txt | head -n 5; echo "金牌总数："; sort -t',' -k2 -nr medals.txt | head -n 5 | awk -F',' '{sum+=$2} END {print sum}'
